Troubleshooting Crashing / Noisy Naomi 2 Motherboard

I recently bought a new NAOMI 2 motherboard to replace the one I currently have that only plays Naomi 1 games (I dropped it and one of the GPUs de-socketed itself).  This board was sold as working and, well, it kinda is…  It has two main issues:

1. It sounds horrendous! Whiny, rattly and grindy at the same time. Horrible to even have switched on. Check out the video below to see / hear what I mean.


2. It keeps freezing after an unspecified period of time in a game.  Complete lock up.  Instantly is fine when reset.  Obviously makes it all a bit useless for actually playing games on.

Naomi 2 Fan Replace (2)So, having cleaned one of these before and noticed the difference I thought I’d do the same here and see if I can work out why it is constantly crashing along the way.  My guess is that it’s clogged up to the heat-sinks with a decade of dust!  First things first, flip the board over and remove the 8 recessed screws holding the plastic case in place.

SCREW

Unscrewing the Board

Below is a pic of the boars as I opened it up.  Surprisingly it was really rather clean inside which actually worries me as I was expecting a big gain from a quick clean

CASE OFF

Full shot of the motherboard with the case off

Whilst I had the cover off I can check out the BIOS to see which version I have.  It’s a EPR-23608B revision which is, apparently, and ‘ Export’ BIOS which supports both the GD ROM and cab linking.  If you have a BIOS and want to know it’s features Sega-Naomi.com have the full list.

BIOS

Bios for the NAOMI board

So, in order to see why it’s so noisy I turned on the system with the covers off and the case fan on it’s side.  The video below shows that I pretty instantly got lucky with two of the noises!

1. The whining and some of the rattling is caused by the case fan.  With it  outside of the case it runs nice and quiet without any trouble (it’s loud ish by default).
2. The grinding and rattling is caused by one of the GPU fans.  It’s really on it’s way out!  Sounds horrid and really isn’t performing well.

Luckily I know the fan for this GPU on my half broken NAOMI 2 board works so I can quickly unscrew the dead fan and replace it with one from the other system. I believe that when the half broken system boots and doesn’t see the second GPU it just turns itself into a NAOMI 1 system.  It seems to run fine with only one fan covering the one working GPU.

FANN02

Unscrewing the GPU fan on a Sega NAOMI 2 Motherboard

Shown below is my sanity test with the new(ish) fan on the GPU and the case fan on its side.  The system is much, MUCH quieter now and it no longer crashes mid game so I think that was down to the faulty fan on the GPU causing a fault or flip out.

N2CF

The Case Fan Off and spinning quietly.

Putting the case fan back in its slot and powering on the system proved another thing.  The sound from the slot in case fan is not damped at all.  In fact, the speed of this fan causes the mount to vibrate on the upper and lower parts of the plastic housing causing a horrible noise.  Granted, it’s much quieter than the GPU fan but still not much fun.  I decided to try out a slightly bodgy solution to prove the point.  White tack!  In theory this should provide a cushion between the fan mount and the case reducing the vibrations and, thereforem the noise.

CFC

Temp Fix for the noisy case fan

It did!  Well, it did for a time.  The fan still vibrates quite forcefully so the effectivness of the tack actually went from “very good” to “meh” in the space of half an hour.  The video below hilights the difference between the board when I first got it and the board now.  Much more playable in the living room but still needs some work to get the vibration gone for good.  I’ll add another post when I work out a solution. Currently i’m thinking thin foam strips or silicone. Silicone is easier but a little more perminant. Foam could be a job to fit and fix but can easily be taken out to return the board to stock.

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About Alec Dunn (LegoYoda)

Alec is an IT guy focused around cloud automation and DevOps. Currently working for ControlCircle he is a firm believer that virtualisation + automation is the best thing to happen to IT since sliced bread! he is also an avid collector of old arcade hardware.
This entry was posted in Arcade Hardware, Hardware, Repair, Teardowns, Troubleshooting and tagged , , , , , , , , . Bookmark the permalink.

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